铝合金搅拌摩擦焊接过程传热和塑性流动数值分析

利用大型计算流体动力学软件FLUENT,建立铝合金板搅拌摩擦焊接过程热流耦合三维有限元模型。通过求解三维质量、动量和能量守恒方程,得到焊接过程粘塑性金属三维流场和温度场。结果表明,相比较搅拌头的进给速度,搅拌头转速对促进其周围塑性金属流动效果明显。同时与纯流场模型相比,热流耦合模型显示金属流动性较充分。此外,仿真得到的温度场得到了实验结果的验证。     

超长散粮筒仓筏板基础混凝土的裂缝控制

1工程概况上海外高桥粮食储备库及码头设施项目是上海市重点工程之一。工程位于浦东新区长江口南岸五号沟地区,距上海市中心约22km,到长江出海口约25km。工程由筒仓、工作塔、熏蒸仓、转接塔及栈桥等组成。其中包括立筒仓60个,平面组合形式为2组3×10排列。筒仓位于工作塔东侧,     

给水管网中旧管段直径及阻力系数的确定

在测试管段比阻的基础上,提出用几种常用水头损失公式计算旧管段直径、海曾——威廉斯公式中系数C和柯尔勃洛克公式中绝对粗糙度k值的方法.并结合实例进行了计算和验证.结果表明:该方法同时考虑了管径及阻力系数对管网水力计算的影响,使旧管道的计算值更接近实际,因而具有广泛的实用性.     

基于OPC技术的WINCC实时数据监控应用

简要介绍了OPC技术,以工程为例,从硬件配置、接线、软件设置给出了具体的实现方法,并以图示给出了Wincc实现OPC连接的具体步骤,使OPC作为一项成型技术,其应用前景将更为广泛。     

微机械陀螺闭环驱动电路的新方法

闭环驱动方式是目前高性能微机械陀螺的主流驱动方式,大部分的闭环驱动电路采用了自动增益控制模块以稳定输出信号的幅度,但是,采用AGC模块会限制电路的线性工作范围,而且输出摆幅有限,因此制约了微机械陀螺系统的灵敏度和稳定性。基于以上不足,在建立微机械陀螺系统等效电路模型的基础上,提出一种新颖的解决方案,采用比较器代替AGC模块,实现对陀螺输出信号幅度的控制,这种方案不仅电路结构更为简单,而且增大了整体电路的线性工作范围,能够始终输出满量程的驱动信号。     

孤北洼陷砂岩超压带分布特征及主控因素

孤北洼陷油气资源丰富,超压带发育。实测地层压力显示,孤北洼陷砂岩超压带主要分布深度为2 800~3 800 m。由于砂岩和泥岩声波时差均与超压有很好的响应关系,且变化幅度和变化趋势一致,故采用Eaton法预测砂岩超压带分布范围,结合实测地层压力进一步分析砂岩超压带分布特征及主控因素。分析结果表明:纵向上,孤北洼陷发育沙一段—东营组底部和沙四段—沙三段2个超压带,其中,沙四段—沙三段为主要超压带;平面上,超压带集中分布于东、西2个次洼,自洼陷中心向凸起及边界断层超压幅度逐渐变小。超压带分布主要受断裂作用、泥岩厚度和含量及烃源岩生油作用等因素控制。     

Hepatocyte-Specific Deficiency of BAP31 Amplified Acetaminophen-Induced Hepatotoxicity via Attenuating Nrf2 Signaling Activation in Mice

Liver-specific deficiency of B-cell receptor-associated protein 31 knockout mice (BAP31-LKO) and the littermates were injected with acetaminophen (APAP), markers of liver injury, and the potential molecular mechanisms were determined. In response to APAP overdose, serum aspartate aminotransferase and alanine aminotransferase levels were increased in BAP31-LKO mice than in wild-type controls, accompanied by enhanced liver necrosis. APAP-induced apoptosis and mortality were increased. Hepatic glutathione was decreased (1.60 ± 0.31 μmol/g tissue in WT mice vs. 0.85 ± 0.14 μmol/g tissue in BAP31-LKO mice at 6 h, p < 0.05), along with reduced glutathione reductase activity and superoxide dismutase; while malondialdehyde was significantly induced (0.41 ± 0.03 nmol/mg tissue in WT mice vs. 0.50 ± 0.05 nmol/mg tissue in BAP31-LKO mice for 6 h, p < 0.05). JNK signaling activation and APAP-induced hepatic inflammation were increased in BAP31-LKO mice. The mechanism research revealed that BAP31-deficiency decreased Nrf2 mRNA stability (half-life of Nrf2 mRNA decreased from ~1.3 h to ~40 min) and miR-223 expression, led to reduced nuclear factor erythroid 2-related factor 2 (Nrf2) signaling activation and antioxidant genes induction. BAP31-deficiency decreased mitochondrial membrane potentials, reduced mitochondria-related genes expression, and resulted in mitochondrial dysfunction in the liver. Conclusions: BAP31-deficiency reduced the antioxidant response and Nrf2 signaling activation via reducing Nrf2 mRNA stabilization, enhanced JNK signaling activation, hepatic inflammation, and apoptosis, amplified APAP-induced hepatotoxicity in mice.     

基于辨识模型的轨迹误差预测方法

为研究轨迹误差的影响因素及规律,进行加工路径优化和轨迹误差预补偿,并提出一种基于辨识模型的轨迹误差预测方法。采用所建立的数控系统前瞻插补模块对G代码进行插补处理,获得离散位置指令;通过进给系统辨识模型对插补后的位置指令进行加工仿真,得到输出位置;根据插补位置数据和仿真得到的输出位置数据对加工轨迹误差进行计算。仿真结果表明:该方法可以快速计算数控机床联动加工时的轨迹误差值和分布情况,为轨迹误差的成因及规律分析、刀具路径的优化及轨迹误差预补偿的实施提供方法和数据支持。     

Enamel coatings mill additives optimization for sulfuric acid corrosion

Different mill additives were optimized to improve enamel coatings anti sulfuric corrosion, the immersive corrosion behaviors in 30 wt. % H₂SO₄ solution for 120 days of the above enamel coatings were investigated by X-ray diffraction, scanning electron microscope-energy dispersive spectrometer, laser scanning confocal microscope, Raman spectra, open-circuit potential, and electrochemical impedance spectroscopy techniques. Results showed that the enamel coating with 12 wt. % quartz mill additives presents the best corrosion resistance. The mill additives significantly reduced the porosity, increased the silicon–oxygen network density, enhanced the gel passivation layer formation ability of enamel coatings, increased the alkaline oxide content, and prevented the ion exchange within the sulfuric acid solution.